1. Field of the Invention
The invention generally relates to the structure of a filter, and more particularly to the structure of an in-tank type fuel filter installed in a fuel tank of a motor vehicle, such as an automobile.
2. Description of Related Art
A known example of an in-tank type fuel filter installed in a fuel tank of a motor vehicle will be hereinafter described with reference to FIG. 7 and FIG. 8.
FIG. 7 shows a fuel tank 1 installed in a motor vehicle, such as an automobile. A fuel pump 3 for delivering fuel to a fuel injection system 4 is disposed in the fuel tank 1. A fuel filter 2 is attached to a coupling member 7, which in turn is attached to the fuel inlet side or upstream side of the fuel pump 3.
The fuel filter 2 is illustrated in detail in FIG. 8. One of the opposite ends of the fuel filter 2 is coupled to the fuel pump 3 via the coupling member 7, while the other end of the fuel filter 2 abuts on a bottom wall 9 of the fuel tank 1. With this arrangement, the fuel pump 3 is able to pump up a sufficient amount of fuel even when the level of the fuel in the fuel tank 1 is lowered.
The fuel filter 2 includes a filter member 5 and a protector 6 disposed inside the filter member 5. The filter member 5 consists of a mesh screen that is formed of a synthetic resin and has a multiplicity of apertures formed therein. The protector 6, which is formed of a synthetic resin, functions to prevent adhesion of two or more sheets of the filter member 5, and ensure a sufficiently large volume of inner space 8 so that a fuel passage can be surely formed in the fuel filter 2.
The known fuel filter 2 as described above is advantageous in that the protector 6 can prevent adhesion of two or more sheets of the filter member 5 to thereby ensure a sufficient volume of inner space 8. In addition, the protector 6 serves to press the filter member 5 of the fuel filter 2 against the bottom wall 9 of the fuel tank 1.
The known fuel filter 2, however, has the following problems. First of all, the provision of the protector 6 results in increases in the overall weight and cost of the fuel filter 2. Secondly, the rigidity of the protector 6 is utilized to press the fuel filter 2 (more specifically, the filter member 5) against the bottom wall 9 of the fuel tank 1, and therefore the filter member 5 is likely to wear, and suffers from a reduced durability. In addition, vibrations of the fuel pump 3 are transmitted to the fuel tank 1 via the protector 6, causing abnormal or unusual noise and making a passenger of the vehicle feel uncomfortable.
Furthermore, the protector 6, which is molded out of a synthetic resin, undergoes deformation (e.g., warpage) when it is immersed in the fuel, and the filter member 5 also deforms along with the protector 6. As a result, the durability of the filter member 5 may deteriorate.
In addition, a corner portion of the protector 6 abrades a portion of the filter member 5 that is in contact with the bottom wall 9 of the fuel tank 1, possibly causing early wear and damage of the filter member 5.
It is therefore an object of the invention to provide a filter that is available at a reduced cost, compact in size, and has an improved durability.
To accomplish the above and/or other objects, there is provided according to one aspect of the invention, which provides a filter that includes (a) at (b) at least one porous member contained in the at least one filter member, and (c) a coupling member having an opening that is open to the at least one porous member so that the porous member communicates with the coupling member. In the filter, the filter member removes foreign matters contained in a liquid, and the liquid from which the foreign matters are removed is discharged through the porous member and the coupling member. With this arrangement, the filter is sure to be provided with sufficiently large inner space and fuel passage(s), without requiring the protector as used in the known filter. Thus, the filter does not suffer from wear that would be otherwise caused by the protector, and therefore the service life of the filter is increased or extended.
In one embodiment of the invention, the filter has a three-layer structure having first and second filter members, and a porous member, which structure is constructed such that the first and second filter members cover upper and lower surfaces of the porous member, respectively. In another embodiment of the invention, the filter has a four-layer structure having first and second filter members and first and second porous members, in which one surface of the first porous member that is not covered by the first filter member is superposed on one surface of the second porous member that is not covered by the second filter member. In a further embodiment of the invention, the filter has a four-layer structure that is formed by bending a two-layer structure comprising one porous member and one filter member covering one surface of the porous member, at a substantially middle portion of the two-layer structure. In any of these embodiments, the filter is surely provided with sufficiently large inner space and fuel passage(s), without requiring the protector as used in the known filter. Thus, the filter does not suffer from wear that would be otherwise caused by the protector, and therefore the service life of the filter is prolonged or extended. Furthermore, the filter can be manufactured in a simplified manner at a reduced cost.
The filter member as indicated above may be formed of filter paper or a non-woven fabric. In this case, the weight of the filter as a whole can be reduced, and the filter can be manufactured in a simplified manner at a reduced cost.
The filter member as indicated above may also be formed from a non-woven fabric and a mesh screen. With the filter member thus formed, the durability of the filter is enhanced, and wear of the filter member, especially when pressed against the bottom wall of the fuel tank, can be advantageously reduced or mitigated. Consequently, the service life of the filter can be prolonged.
In another embodiment of the invention, the coupling member is provided on the upper one of the filter members. With this arrangement, the entire area of the lower filter member is able to abut on the bottom wall of the fuel tank, so that the filter can pump up fuel without fail even if the fuel level in the tank is lowered.
In a still another embodiment of the invention, the coupling member extends from the upper filter member to the lower filter member. In this case, the coupling member can surely hold the filter, while preventing deformation thereof.
In a yet another embodiment of the invention, the coupling member is provided on a side face of the filter member. With this arrangement, a fuel pump disposed within the fuel tank can be located in the vicinity of the inner wall of the fuel tank. Thus, the mounting position of the fuel pump can be determined with increased flexibility.